Stabilization process



United States Patent STABILIZATION rnocnss William K. T. Gleim, OrlandPark, Ill., assiguor to Universai Gil Products Company, Chicago, IIL, acorporation of Delaware No Drawing. Appiication February 16, 1952,Serial No. 271,980

20 Qiaims. (Cl. 99-163) This application relates to a stabilizationprocess and more particularly to a method of preventing deterioration ofunstable organic substances during storage, transportation or treatment,by incorporating therein a novel inhibitor.

, The present invention is particularly applicable to the stabilizationof food products which generally are of animal, vegetable or mineralorigin, including edible fats and oils which tend to become rancid,especially during long periods of storage prior to use. Typicalrepresentatives of these oils include linseed oil, menhaden oil, codliver oil, castor oil, olive oil, rapeseed oil, coconut oil, palm oil,corn oil, sesame oil, peanut oil, babassu oil, butter, fat, lard, beeftallow, etc., as well as hydrogenated fats and oils such as are soldunder various trade names. It is understood that other oils and fats maybe treated within the scope of the present invention, including oils andfats which previously have been subjected to various treatments, such asblowing with air, heat treatment, etc.

Other specific organic substances which undergo deterioration and towhich the present invention is applicable include motor fuel andparticularly olefinic gasolines such as cracked gasoline and polymergasoline, etc., kerosene, lubricating oil, diesel oil, fuel oil, etc.,drying oils, rubber, plastics, waxes, monomers, resins, adhesives,photographic developers, synthetic unsaturated compounds, etc.

In one embodiment the present invention relates to a method ofstabilizing an organic compound subject to oxidative deterioration whichcomprises adding thereto an inhibitor comprising an alkylated flavonecompound having at least one hydroxy substituent.

In a specific embodiment the present invention relates to lardcontaining, as an inhibitor against rancidity, butylateddihydroquercetin.

I have found that butylation of dihydroquercetin results in an inhibitorcompound which is approximately two and one-half times more potent thandihydroquercetin as an inhibitor to retard oxidative deterioration of anorganic substance. This unexpected improvement considerablv enhances thefeasibility of flavone compounds as inhibitors and furthermore thealkylated compounds are of increased solubility in most substrates. Thisfurther enhances the desirability of the use of the flavone compounds asinhibitors.

The alkylated flavone compounds for use in accordance with the presentinvention may be represented by the following general formula:

Where Y is selected from hydrogen, alkyl or hydroxy groups, and at leastone Y is an alkyl group and at least one Y is a hydroxy group.

It will be noted that the numbering of the oxygen and carbon atoms hasbeen indicated. This numbering system will be used throughout thepresent specifications and claims.

The alkylated flavone compounds of the present in- 2,694,645 PatentedNov. 16, 1954 "ice As hereinbefore set forth, the alkylated flavonecompounds of the present invention must contain at least one alkyl groupand at least one hydroxy group. Preferred compounds comprise those inwhich two of the Y substituents are hydroxy groups in a position orthoor para to each other, and one of the Y substituents is a tertiary alkylgroup, while the remaining Y is hydrogen. Specific compounds in thisgroup include tertiary alkylated-5,6-dihydroxy flavones, tertiaryalkylated-5,8-dihydroxy flavones, tertiary alkylated 6,7 dihydroxyflavones, tertiary alkylated-7,8-dihydroxy flavones, tertiaryalkylated-2',3-dihydroxy flavones, tertiary alkylated-2',5'-dihydroxyflavones, tertiary alkylated-3,4- dihydroxy flavones, tertiaryalkylated-3',6'-dihydroxy flavones, tertiary alkylated-4',5-dihydroxyflavones, tertiary alkylated-5,6-dihydroxy flavones, etc. Other than therequirement that at least one Y is an alkyl group and the other Y is ahydroxy substituent, the flavone compounds may contain othersubstituents attached to one or more of the rings. Thus additionalinhibitor compounds include alkylated chrysin (alkylated-5,7-dihydroxyflavone), alkylated luteolin (alkylated-5,7,3',4- tetrahydroxy flavone),alkylated quercetin (alkylated- 3,5,7,3',4-pentahydroxy flavone),alkylated myricetin (alkylated-35.73,4',5-hexahydroxy flavone),alkylated rhamnetin (alkylated 3,5,3,4'-tetrahydroxy-7-methoxy flavone),alkylated rhamnazin (alkylated-3,5,4'-trihydroxy-7,3'-dimethoxyflavone), etc. It will be noted that all of the above compounds containat least two hydroxy substituents.

Also included in the alkylated flavone compounds for use in accordancewith the present invention are al kylated flavone compounds having thebridge oxygen in the 1-position and a phenyl group in the 3-position.Flavones having the phenyl group in the 3-position are iso-fiavones andthe term isoflavones, therefore, is used in the present specificationsand claims to mean a flavone compound having the phenyl ring attached inthe 3-position with the bridge oxygen in the 1-position. Also includedin the alkylated flavone compounds are alkylated xanthones includingsuch compounds as alkylated euxanthone (alkylated1,7-dihydroxy-Xanthone), alkylated gentisein (alkylated1,7-dihvdroxy-3-methoxy-xanthone), etc. It is understood that thealkylated isoflavone and xanthone compounds may be substituted byhydroxy or other substituents as hereinbefore set forth.

When the flavone compound contains a hydroxy substituent in the3-position, the compound will be a flavonal. The flavonal may besubstituted in the manner hereinbefore set forth and thus includes suchcompounds as alkylated galangin (alkylated-5.7-dihydroxy flavonal),alkylated datiscetin (alkylated 5.7.2 tr ihv dr ox y fiavanol),alkylated kaempherol (alkylated-5.7.4'-trihydroxy fiavanoll, alkylatedmorin (alkylated-5.7,2',4'- tetrahydroxy flavanol), alkylatedquercetagetin (alkylated 5,6,7.3',4 pentahydroxy fiavanol), alkylatedgossypetin (alkylated-5.7,8,3'-tetrahydroxy flavanol), etc. Alsoincluded in the flavone compounds are alkylated flavanone compoundswhich may be substituted similarly as described above or otherwise,provided the substituents contain at least one alkyl group and at leastone hydroxy substituent. Alkylated dihydroquercetin(alkylated-3,5,7,3',4'-pentahydroxy flavanone) is a preferred compound.

When one Y is hydrogen, one Y is a tertiary alkyl group and the othertwo Y substituents are hydrogen, preferred compounds include flavones,flavanols, or fiavanones containing the following substituents:5-hydroxy-6-tertiary alkyl, 6-hydroxy-7-tertiary alkyl,7-hydroxy-S-tertiary alkyl, 6-hydroxy-5-tertiary alkyl,7-hydroxy.-6-tertiary alkyl, 8-hydroxy-7-tertiary alkyl,'2"-hydroxy-3'-tertiary alkyl, 3'-hydroxy-4-tertiary alkyl, 4-hydroxy-5'-tertiary alkyl, 5'-hydroxy-6'-tertiary alkyl, 3'-hydroxy-2'-tertiary alkyl, 4'-hydroxy-3-tertiary alkyl, 5-hydroxy-4'-tertiary alkyl, 6'-hydroXy-5'-tertiary alkyl, etc.

The alkylated substitutent preferably comprises an alkyl group,including a branched chain substituent and particularly a tertiary alkylsubstituent. Thus the tertiary alkyl group may comprise one or more oftertiary butyl, tertiary amyl, tertiary hexyl, tertiary heptyl, tertiaryoctyl, tertiary nonyl, tertiary decyl, tertiary undecyl, tertiarydodecyl, etc. Other branched chain alkyl groups include secondary alkylsubstituents including secondary butyl, secondary amyl, secondary hexyl,etc., and isoalkyl substituents include isoamyl, isohexyl, etc. Ingeneral, alkyl groups containing from 4 to 8 carbon atoms per group arepreferred and, when more carbon atom substituents are desired, thesubstitution preferably is obtained through the use of two or more alkylgroups containing from 4 to 8 carbon atoms per group. In general thetotal number of carbon atoms in the total substituents preferably doesnot exceed about 25.

The fiavone compounds specifically set forth above are representative ofthe large number of compounds which may be employed in accordance withthe present invention and are not to be considered as being limitedthereto. It will be noted that a large number of different compounds maybe employed and that all of these compounds are not necessarilyequivalent but that all of them will be eifective in retarding oxidativedeterioration of the organic substance.

Alkylation of the fiavone or flavanone compound may be eifected in anysuitable manner. Generally the alkylation may be eifected by thereaction of the desired fiavone or flavanone compound with an olefin oran alcohol in the presence of a suitable catalyst. For example,dihydroquercetin may be reacted with tertiary butyl alcohol in thepresence of 85% phosphoric acid to form butylated dihydroquercetin. Itis believed that this reaction includes both alkylation and dehydrationof the dihydroquercetin, thus indicating formation of a fiavone from theflavanone.

The fiavone compound may be obtained from any suitable source orprepared in any suitable manner. For example, dihydroquercetin has beenobtained from Douglas fir heartwood. The flavanones may be synthesizedfrom polyhydroxychalcones obtained from suitably substitutedbenzaldehydes and acetophenones by the Claisen reaction. One hydroxygroup must be ortho to the keto group in order to permit closing of thering. Flavanones also may be synthesized by the reaction of hydroxyacetophenones with acid anhydrides and sodium salts of aromatic acids ina Perkin type reaction.

The inhibitor generally is added to the organic substance to bestabilized in amounts of less than about 1% by weight and preferablywithin the range of from about 0.0001% to about 0.5% by weight. Theinhibitor may be used alone or in conjunction with inhibitor activatorsor synergists, dyes, antiknock agents, etc., depending upon the organicsubstance being treated. For example, when used in edible fats and oils,a synergist, such as citric acid, phosphoric acid, ascorbic acid, etc.,and perhaps a metal deactivator, may be used along with the inhibitor.On the other hand, when used in gasoline, tetraethyl lead, a metaldeactivator, a dye and perhaps an inhibitor activator, such asparticular types of alkylene polyamines, may be used.

The following examples are introduced to illustrate further the noveltyand utility of the present invention but not with the intention ofunduly limiting the same.

EXAMPLE I This example illustrates the improved results obtained by theuse of tertiary butylated dihydroquercetin as compared withdihydroquercetin. The butylated dihydro quercetin was prepared by thereaction of dihydroquercetin with tertiary butyl alcohol in the presenceof 85% phosphoric acid as hereinbefore set forth.

The lard used for these runs had a normal stability period of 5 hours asdetermined by the Swift test. This test is described in detail in thearticle by A. E. King, H. L. Roschen, and W. H. Irwin, which appeared inthe Oil and Soap, vol. X, No. 6, pages 105 to 109 (1933). In general,this test comprises bubbling air through a sample of the lard untilrancidity is determined organoleptically and by peroxide formation. Theresults reported in the following table are the number of hours untilthe lard developed a peroxide number of 20.

It will be noted that the alkylated dihydroquercetin is about 2 /2 timesas effective as the unalkylated dihydroquercetin. Furthermore, thealkylated product is more soluble in lard than is dihydroquercetin and,therefore, is considerably more attractive for this use.

EXAMPLE II This example illustrates the results obtained in thestabilization of another sample of the lard as determined in the Schaaloven test. The Schall oven test is a standard test for determining thestability of lard. The lard is maintained in the oven at F., ranciditybeing determined organoleptically, and the time until rancidity developsis reported in days. The lard had a stability period of 8 days asdetermined in the Schaal oven test. Upon the addition of 0.02% by weightof tertiary butylated dihydroquercetin, the stability of the lard wasincreased to 93 days. Thus it is noted that the butylated fiavonecompound was a very elfective inhibitor to retard rancidity development.

EXAMPLE III Bacon slabs may be stabilized against rancidity by soakingthe slabs in an aqueous solution containing 0.2% by weight of butylateddihydroquercetin.

EXAMPLE IV Corn oil may be stabilized against rancidity by incorporatingtherewith 0.1% by weight of tertiary hexylated dihydroquercetin.

I claim as my invention:

1. A method of stabilizing an organic substance subject to oxidativedeterioration which comprises incorporating therein an alkylated fiavonecompound having at least one hydroxy substituent.

2. A method of stabilizing an organic substance subject to oxidativedeterioration which comprises incorporating therein a tertiary alkylatedfiavone compound having at least one hydroxy substituent.

3. A method of stabilizing an organic substance subject to oxidativedeterioration which comprises incorporating therein a teritary alkylateddihydroquercetin.

4. A method of stabilizing an edible fat or oil against rancidity whichcomprises incorporating therein tertiary butylated dihydroquercetin.

5. A method of stabilizing an organic substance subject to oxidativedeterioration which comprises incorporating therein an alkylated fiavonecompound having two hydroxy substitutents in a position ortho to eachother.

6. A method of stabilizing an organic substance subject to oxidativedeterioration which comprises incorporating therein an alkylated fiavonecompound having two hydroxy substituents in a position para to eachother.

7. A method of stabilizing an organic substance subject to oxidativedeterioration which comprises incorporating therein an alkylated fiavonecompound having a hydroxy substituent and a tertiary alkylatedsubstitutent in a position ortho to the hydroxy substituent.

8. An organic substance subject to oxidative deterioration containing,as an inhibitor for said deterioration, an alkylated fiavone compoundhaving at least one hydroxy substituent.

9. An organic substance subject to oxidative deterioration containing,as an inhibitor for said deterioration, a tertiary alkylated fiavonecompound having at least one hydroxy substituent.

10. An organic substance subject to oxidative deterioration containing,as an inhibitor for said deterioration, tertiary butylateddihydroquercetin.

11. An edible fat or oil subject to oxidative deterioration containing,as an inhibitor for said deterioration, an alkylated flavone compoundhaving at least one hydroxy substituent.

12. An edible fat or oil subject to oxidative deterioration containing,as an inhibitor for said deterioration, an alkylated flavone compoundhaving two hydroxy substituents in a position ortho to each other.

13. An edible fat or oil subject to oxidative deterioration containing,as an inhibitor for said deterioration, an alkylated flavone compoundhaving a hydroxy substituent and a tertiary alkylated substituent in aposition ortho to the hydroxy substituent.

l4. Lard containing, as an inhibitor against rancidity, an alkylatedflavone compound having at least one hydroxy substituent.

15. Lard containing, as an inhibitor against rancidity, an alkylatedflavone compound having two hydroxy substituents in a position ortho toeach other.

16. Lard containing, as an inhibitor against rancidity, an alkylatedflavone compound having two hydroxy substituents in a position para toeach other.

17. Lard containing, as an inhibitor against rancidity, an alkylatedflavone compound having a hydroxy substituent and a tertiary alkylatedsubstituent in a position ortho to the hydroxy substituent.

18. Lard containing, as an inhibitor against rancidity, tertiarybutylated dihydroquercetin.

19. Vegetable oil containing, as an inhibitor against rancidity, analkylated flavone compound having at least one hydroxy substituent.

20. Vegetable oil containing, as an inhibitor against rancidity, analkylated flavone compound having a hydroxy substituent and a tertiaryalkylated substituent in a position ortho to the hydroxy substituent.

References Cited in the file of this patent UNITED STATES PATENTS (pages243-245).

Kurth et al., J. Am. Oil-Chem. Society, October 1951 (pages 433-436).

1. A METHOD OF STABILIZING AN ORGANIC SUBSTANCE SUBJECT TO OXIDATIVEDETERIORATION WHICH COMPRISES INCORPORATING THEREIN AN ALKYLATED FLAVONECOMPOUND HAVING AT LEAST ONE HYDROXY SUBSTITUENT.